/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.iotdb.db.queryengine.plan.relational.planner.iterative;

import org.apache.iotdb.db.queryengine.plan.planner.plan.node.PlanNode;
import org.apache.iotdb.db.queryengine.plan.planner.plan.node.PlanVisitor;

import java.util.List;
import java.util.stream.Collectors;

import static java.util.Objects.requireNonNull;

public final class Plans {
  public static PlanNode resolveGroupReferences(PlanNode node, Lookup lookup) {
    requireNonNull(node, "node is null");
    return node.accept(new ResolvingVisitor(lookup), null);
  }

  private static class ResolvingVisitor extends PlanVisitor<PlanNode, Void> {
    private final Lookup lookup;

    public ResolvingVisitor(Lookup lookup) {
      this.lookup = requireNonNull(lookup, "lookup is null");
    }

    @Override
    public PlanNode visitPlan(PlanNode node, Void context) {
      List<PlanNode> children =
          node.getChildren().stream()
              .map(child -> child.accept(this, context))
              .collect(Collectors.toList());

      return node.replaceChildren(children);
    }

    @Override
    public PlanNode visitGroupReference(GroupReference node, Void context) {
      return lookup.resolve(node).accept(this, context);
    }
  }

  private Plans() {}
}
